The present invention is especially related to improved methods and apparatus for grinding and sharpening spiral tool cutting edges, and particularly those which do not have a circumferential edge and cannot be driven in rotation by an electric motor or the like as they are presented to the grinding wheel. Various tool supporting attachments have been proposed in the past, most of which are of the type wherein the tool is continuously revolved by a motor driven member as it is moved to the grinding wheel and are exemplified in the following U.S. Pat. Nos. 1,858,235 2,411,972 2,741,074 3,118,260 3,594,961.
The present attachment is similarly mounted on a tool table or slide which moves linearly to the vicinity of the grinding wheel peripheral edge surface, and essentially provides a true hand operated attachment in the sense that the spiral cutting tool is both revolved and fed axially manually during the grinding operation so that the "feel" of the operator's hands, and skill in manipulating the attachment, ensures that optimum cutting edges are ground in a most expeditious and accurate manner. The tool grinder which is used may be the Cincinnati Milling Machine Co. (Cincinnati, Ohio, U.S.A.) No. 2 machine which is described in the company's publication No. M-1951-2, copyrighted in 1963.
A prime object of the invention is to provide a three-point tool support that will allow one hand to comfortably revolve a cutting tool to be ground or sharpened to the desired position and then present its edges to the grinding wheel for grinding via a manually controlled revolution or partial revolution determined by the helical angle of the cutting tool.
A more specific object of the invention is to provide an attachment having a lever pivoted on the centerless support for the spiral cutting tool, the lever mounting a freely rotatable roller above the centerless support which can be manipulated by the thumb of an operator while, with the same hand, he holds a fixed grip and squeezes the lever to control the pressure on the roller as the tool is moved in a grinding pass. Thus, the force with which the roller revolving the tool is held in frictional engagement with the tool is controlled by the tool grinder during the grinding pass.
Another object of the invention is to provide a fast comfortable way in which the hand that controls the fixture, can also manually release the tool or workpiece.
Another specific object of the invention is to provide an attachment which allows the attachment-controlling hand to "feel" the actual grinding of the tool. This permits the operator to determine the proper speed at which the other hand should present the workpiece to the grinding wheel to allow the grinding wheel to spark out and hold precise tolerances on the cutting edges of the tool.
Still another object of the invention is to provide a mechanism of the character described having a pivotally mounted centerless support assembly for the tool which can be optionally locked or released and is useful to permit the operator to pivot the tool downwardly to miss the wheel on either the forward or return passes.